Analysis of Data Clusters Obtained by Self-Organizing Methods

The self-organizing methods were used for the investigation of financial market. As an example we consider data time-series of Dow Jones index for the years 2002-2003 (R. Mantegna, cond-mat/9802256). In order to reveal new structures in stock market behavior of the companies drawing up Dow Jones index we apply SOM (Self-Organizing Maps) and GMDH (Group Method of Data Handling) algorithms. Using SOM techniques we obtain SOM-maps that establish a new relationship in market structure. Analysis of the obtained clusters was made by GMDH.Comment: 10 pages, 4 figure

Application of density functional theory in the synthesis of electroactive polymers

A wide range of conjugated organic compounds undergo anodic electropolymerisation to produce polymers of high conductivity. However, electrooxidation does not always result in the formation of electroactive materials, since some reactions produce insulating films or soluble oligomers. Density functional theory (DFT) has been used to predict the outcome of electropolymerisation reactions by calculating the unpaired electron π-spin density distribution of monomeric radical cations, in order to determine coupling positions in the resultant polymers. π-Spin densities calculated for pyrrole, thiophene and (E)-stilbene are found to be in good agreement with experimental values. DFT has been used to investigate the low conductivity and redox inactivity of poly[(E)-3-styrylthiophenes] and poly[(E)-2-styrylheterocycles]. High positive spin densities at the alkene spacer linkage in the corresponding monomeric radical cations were found, suggesting crosslinking of the polymers via the double bond. In contrast, electroactive polymers of improved conductivity are formed from the electropolymerisation of some (Z)-2-α,β-diarylacrylonitriles. For these monomers, DFT calculations show the positions of highest spin density to be located at the α-positions of the heterocyclic rings, suggesting the presence of α,α′-linked monomeric couplings necessary for electroactivity

Coordination of Nucleases and Helicases during DNA Replication and Double-strand Break Repair

Nucleases and helicases are involved in numerous steps in DNA replication and repair. Nucleases act on intermediates in DNA replication created by DNA polymerases (Chapter 4) and helicases (Chapter 3). They can create substrates for repair as in Okazaki fragment processing (OFP) and homologous recombination. They can also create substrates for activation of a checkpoint response, or participate in downregulation of checkpoints. In the special case of telomere replication, they are also involved in essential processing steps (Chapter 8). Nucleases known to act during DNA replication include Dna2, Rad27, Mre11, Sae2, Exo1, RNaseH, Yen1 andMus81/Mms4. Of these, Dna2, Exo1 and Mre11 are of particular interest because they have been identified as crucial activities that initiate repair of double-strand breaks (DSBs) by homologous recombination and thus form an intrinsic link between DNA replication and repair of DSBs derived from replication fork failure. The action of the nucleases is coordinated with those of a number of helicases and is discussed here in the context of a network of their interactions that combine to maintain genome integrity during DNA replication

Coordination of Nucleases and Helicases during DNA Replication and Double-strand Break Repair

Nucleases and helicases are involved in numerous steps in DNA replication and repair. Nucleases act on intermediates in DNA replication created by DNA polymerases (Chapter 4) and helicases (Chapter 3). They can create substrates for repair as in Okazaki fragment processing (OFP) and homologous recombination. They can also create substrates for activation of a checkpoint response, or participate in downregulation of checkpoints. In the special case of telomere replication, they are also involved in essential processing steps (Chapter 8). Nucleases known to act during DNA replication include Dna2, Rad27, Mre11, Sae2, Exo1, RNaseH, Yen1 andMus81/Mms4. Of these, Dna2, Exo1 and Mre11 are of particular interest because they have been identified as crucial activities that initiate repair of double-strand breaks (DSBs) by homologous recombination and thus form an intrinsic link between DNA replication and repair of DSBs derived from replication fork failure. The action of the nucleases is coordinated with those of a number of helicases and is discussed here in the context of a network of their interactions that combine to maintain genome integrity during DNA replication

The influence of distance and level of care on delivery place in rural Zambia: a study of linked national data in a geographic information system.

BACKGROUND: Maternal and perinatal mortality could be reduced if all women delivered in settings where skilled attendants could provide emergency obstetric care (EmOC) if complications arise. Research on determinants of skilled attendance at delivery has focussed on household and individual factors, neglecting the influence of the health service environment, in part due to a lack of suitable data. The aim of this study was to quantify the effects of distance to care and level of care on women's use of health facilities for delivery in rural Zambia, and to compare their population impact to that of other important determinants. METHODS AND FINDINGS: Using a geographic information system (GIS), we linked national household data from the Zambian Demographic and Health Survey 2007 with national facility data from the Zambian Health Facility Census 2005 and calculated straight-line distances. Health facilities were classified by whether they provided comprehensive EmOC (CEmOC), basic EmOC (BEmOC), or limited or substandard services. Multivariable multilevel logistic regression analyses were performed to investigate the influence of distance to care and level of care on place of delivery (facility or home) for 3,682 rural births, controlling for a wide range of confounders. Only a third of rural Zambian births occurred at a health facility, and half of all births were to mothers living more than 25 km from a facility of BEmOC standard or better. As distance to the closest health facility doubled, the odds of facility delivery decreased by 29% (95% CI, 14%-40%). Independently, each step increase in level of care led to 26% higher odds of facility delivery (95% CI, 7%-48%). The population impact of poor geographic access to EmOC was at least of similar magnitude as that of low maternal education, household poverty, or lack of female autonomy. CONCLUSIONS: Lack of geographic access to emergency obstetric care is a key factor explaining why most rural deliveries in Zambia still occur at home without skilled care. Addressing geographic and quality barriers is crucial to increase service use and to lower maternal and perinatal mortality. Linking datasets using GIS has great potential for future research and can help overcome the neglect of health system factors in research and policy. Please see later in the article for the Editors' Summary

An exploration of sex-specific linkage disequilibrium on chromosome X in Caucasians from the COGA study

This paper explores the decay of linkage disequilibrium (LD) on the autosomes and chromosome X. The extent of marker-marker LD is important for both linkage and association studies. The analysis of the Caucasian sample from the Collaborative Study on the Genetics of Alcoholism study revealed the expected negative relationship between the magnitude of the marker-marker LD and distance (cM), with the male and female subgroups exhibiting similar patterns of LD. The observed extent of LD in females was less across the pseudoautosomal markers relative to the heterosomal region of chromosome X. Marked differences in LD patterns were also observed between chromosomes X and the 22 autosomes in both males and females

Black-Scholes option pricing within Ito and Stratonovich conventions

Options financial instruments designed to protect investors from the stock market randomness. In 1973, Fisher Black, Myron Scholes and Robert Merton proposed a very popular option pricing method using stochastic differential equations within the Ito interpretation. Herein, we derive the Black-Scholes equation for the option price using the Stratonovich calculus along with a comprehensive review, aimed to physicists, of the classical option pricing method based on the Ito calculus. We show, as can be expected, that the Black-Scholes equation is independent of the interpretation chosen. We nonetheless point out the many subtleties underlying Black-Scholes option pricing method.Comment: 14 page

Do maternal perceptions of child eating and feeding help to explain the disconnect between reported and observed feeding practices?: A follow-up study

Research demonstrates a mismatch between reported and observed maternal feeding practices. This mismatch may be explained by maternal cognitions, attitudes, and motivations relating to dyadic parent–child feeding interactions. These complex constructs may not be apparent during observations nor evidenced in self-report questionnaire. Therefore, the aim of this study was to use a qualitative approach to gain a more nuanced and contextualized understanding of (a) maternal perceptions of children's food intake control; (b) how parent–child mealtime interactions influence maternal feeding practices; and (c) ways in which mothers may promote healthy child eating and weight outcomes. Semistructured telephone interviews were conducted with 23 mothers (M = 38.4 ± 3.7 years of age) of preschool-aged children (M = 3.8 ± 0.6 years of age, 19 were normal weight, 14 were girls), who had previously completed child feeding questionnaire and participated in two home-based mealtime observations, 12 months apart. Interviews were recorded, transcribed, and themes extracted to create the database. Four major themes emerged: (a) Maternal confidence in children's ability to regulate food intake is variable; (b) Implementing strategies for nurturing healthy relationships with food beyond the dining table; (c) Fostering positive mealtime interactions is valued above the content of what children eat; and (d) Situation-specific practices and inconsistencies. Findings indicate that maternal feeding practices are shaped by both parent and child influences, and child feeding is mostly guided by controlling the family food environment, rather than by directly pressuring or restricting their child's eating. Results also highlighted the need for research to consider both parent and child influences on child feeding

New perturbative solutions of the Kerr-Newman dilatonic black hole field equations

This work describes new perturbative solutions to the classical, four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions do not require the black hole to be slowly rotating. The unperturbed solution is taken to be the ordinary Kerr solution, and the perturbation parameter is effectively the square of the charge-to-mass ratio $(Q/M)^2$ of the Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror) symmetry for the theory, which maps the small coupling sector to the strong coupling sector ($\phi \to -\phi$). We also calculate the gyromagnetic ratio of the black hole.Comment: Revtex, 27 page